Category: Amusing Facts

Hues of hydrangeas

Hydrangeas are in full bloom this time of year.  I snapped these photos yesterday of several hydrangeas, all planted along the same strip of land.  Just look at the different colors:

Why so many colors? Most of you probably know that genetics play a role, as does soil pH.  But there’s much more to it than simple soil chemistry and genes.

1. pH:  Strongly acidic soils produce blue hydrangeas, while slightly acid to slightly alkaline soils favor pink or red flowers.  Soil pH can be modified by adding lime to raise soil pH or ammonium sulfate to acidify the soil.

2. Aluminum: Aluminum, a toxic heavy metal, is required for blue hydrangeas. Like other metallic elements, aluminum binds tightly to clay particles under alkaline conditions. As the pH becomes more acidic, aluminum becomes soluble and can be taken up by plant roots.

3. Nutrients: Relative concentrations of phosphate, nitrogen, and potassium have significant impacts on the uptake and activity of aluminum.

4. Pigments: Blue hydrangea flowers depend on the formation of a complex among three partners: an anthocyanin called delphinidin with a sugar attachment, a phenolic acid co-pigment, and aluminum. Co-pigment differences among species and cultivars will influence flower color.

And here’s an interesting factoid about hydrangeas: ever notice that they are rarely bothered by insects or other animals? Accumulation of a toxin like aluminum in their tissues may be the reason.

GP Hit List: Ligustrum sinense (Chinese Privet)

[And I don’t mean “greatest hits”, I mean “Mafia hit”]

Gardeners, yardeners, and designers are on a perpetual lookout for a good hedge species. Hedges are useful in so many ways: providing backdrop for a border, making good neighbors, containing football players, etc.  In reference to the latter, the field at Sanford Stadium at the University of Georgia (cue woofing!) is known as “Between the Hedges”.  In the extensive lore of UGA football, everyone makes like it’s some sacred plant, but (gasp!) it’s just plain ol’ privet. Aside to Jeff, my fellow UGA alum: CNN just reported the dubious distinction that Georgia is the #1 party school in the country (again).  Maybe this is why I can’t remember the Krebs Cycle.


Variegated Chinese Privet in all its shrubby glory; photo from University of Arkansas Cooperative Extension.

Back to privet. Designers of D.O.T. landscapes such as medians and interchanges seem especially enamored. Clouds of variegated privet (L. sinense ‘Variegatum’) dot interstates throughout the South.  Yes, it’s tough, useful, variegated, and touted as “wildlife friendly” by some leading gardening resources. The berries are indeed good bird food; therein lies the problem. Seeds pooped out by birds results in the green, non-variegated version – much more vigorous and deposited everywhere. For the record, the variegated form also reverts like crazy.

My family’s farm in northeast Georgia is bordered by the North Fork of the Broad River. Over the years, the river bottom, and then the fence lines at all elevations, have filled with privet. It is, pardon my language, a total bitch to remove and almost impossible to eradicate.  The State Botanical Garden of Georgia in Athens has an entire squad dedicated to eliminating it from acres of river bottom; ironically, only a few miles from Sanford Stadium. Thought of mostly as a Zone 7-9 plant; we have lots of it in the woods here in the mountains – an entire zone cooler.


Distribution of L. sinense; USDA PLANTS Database http://plants.usda.gov/

Ligustrum sinense is on at least two official Invasive and Noxious Weeds lists by the Southeast Exotic Pest Plant Council and Florida Exotic Pest Plant Council as well as several international lists.  Nursery growers and landscapers across the South know these things. So why, why, why, do they continue to produce and spec it?  “Variegated foliage sells. People see it, like it, and then ask for it. It’s a bread-and-butter item.”  This comment came from the owner of a fairly large nursery that sells to independent garden centers.

Our industry yelps whenever a state or federal mandate threatens to impose restrictions on a best-seller (Hedera helix, for recent example).  There are LOTS of terrific woody plants out there, people.  The Dirr book is now up to 1250 pages – thumb through and pick a few alternatives. Cease and desist with the Chinese privet.

 

Why do nurseries sell this plant?

I wish I were more like Holly…wandering around nurseries finding pretty and unusual annuals and perennials to get excited about.  Instead, I seem to gravitate to plants that annoy me.

Today while looking for some trellises (for those containerized Clematis vines that I’ve been torturing) I saw pots of the Equisetum hyemale (“a tall, evergreen, spreading, reed-like grass”) for sale:

 

As readers of this blog surely know, Equisetum spp. – or horsetails – are not grasses but primitive relatives of ferns.  That taxonomic blunder aside, the thought of deliberately planting any Equisetum species in a landscape sends shivers down my spine.

Now E. hyemale is not as weedy as E. arvense, but in nearly every seminar I give on controlling weeds with mulch someone asks about getting rid of horsetails.  Short answer – you pull.  And pull and pull.  There’s no good herbicide for them, nothing seems to eat them, and they spread aggressively.

And speaking of eating, did you know that horsetails are poisonous?  They contain an enzyme (thiaminase) that deactivates thiamin (vitamin B1) in the unfortunate consumer’s body.  The most common victims of horsetail poisoning, ironically, are horses.  Horsetails are considered noxious weeds in pastures used for grazing – and yes, they are native to the United States.

Sure, horsetails are interesting looking plants.  But do you really want something in your garden that the production nursery describes as having “indefinite spread?”  And how does keeping them in a pot, as one production nursery recommends, keep them from spreading spores?  Especially if you plant them “in or around ponds and streams?”

I just think this is such a bad idea for home landscapes.  Even if it is a native species.

John Bartram Lives!

Yep, there he is. Showed up at our state Master Gardener College, just last week. I even went to dinner with him. The snake-on-a-stick startled the bartender just a bit.



The elder Bartram (his son William was also a great botanist and explorer) was the Royal Botanist to King George III and a member of the Royal Academy of Sciences, Stockholm. As with many of the Great Plant Explorers, his life combined botany with politics,
adventure, and lust [for plants,anyway]. Someone should make a movie…

Probably best know as the discoverer of the soon-to-be-doomed little tree, Franklinia
alatamaha, he also was responsible for the introduction of lots of
other North American native garden staples such as rhododendrons,
Kalmia, and deciduous magnolias. Bartram died in 1777, but has recently been resurrected by Kirk Brown, master thespian and all-around talented guy.

Kirk works with Joanne Kostecky Garden Design in Allentown, PA, and is a director for Garden Writers of America.  But his passion for the life and times of fellow Pennsylvanian John Bartram takes the audience far beyond the usual gardening lecture. His presentation "John Bartram: The King’s Gardener" unveils the travels, collections, and psyche of the father of the nursery industry in the original thirteen colonies. I love the review by Stephanie Cohen (The
Perennial Diva!) "Kirk Brown did not imitate John Bartram, he actually
became him…anyone who has an interest in history or horticulture will
be spellbound by this presentation."  She’s absolutely correct. For more on John/Kirk, check out www.johnbartramlives.com.

Cornmeal myth busted

As my colleague Fred Hoffman says, the horticultural silly season is upon us. This week I heard from one of our European readers, questioning the use of cornmeal as a fungicide. He referenced an online article entitled “Cornmeal has powerful fungicidal properties in the garden.” He hadn’t been able to find any reliable information and thought it might make a good topic for our blog. So Johannes, this rant’s for you!

If you’ve followed the link to column in question, you’ll see that the original “research” is attributed to one of Texas A&M’s research stations in Stephenville, TX. But it’s not really research – it’s just an observation on what happens when you don’t plant the same crop two years in a row; in this case, rotating corn and peanuts reduces peanut pathogens. This is hardly news – it’s one of the reasons agricultural scientists recommend crop rotation as part of an IPM program. And have for decades.

Then we’re referred to “further research” (at an undisclosed location) where cornmeal was shown to contain “beneficial organisms.” Well, no, cornmeal doesn’t contain organisms, beneficial or otherwise. Microbes can grow on cornmeal, and in fact cornmeal agar is commonly used in labs as a growth medium for many species of fungi. And has been for decades.

Nevertheless, we’re informed that a gardening personality has “continued the study and finds cornmeal effective on most everything from turf grass to black spot on roses.” This is directly refuted by Dr. Jerry Parsons, who by happy coincidence is an extension faculty specialist at Texas A&M. His informative (and hilarious) column on brown spots in lawns states “Lately there have been claims made that corn meal and a garlic extract is effective. This is absolutely false! Everyone trying to do the “environmentally friendly-to-a-fault” thing have been wasting their money. They would have been better off making corn bread and using their garlic for cooking purposes!”

Dr. Parsons continues: “Let me explain how these University tests and recommendations have been misrepresented in a desperate attempt to find an organic fungicide. The corn meal was investigated by a Texas A&M pathologist as a way to produce parasitic fungi used to control a fungus which occurs on peanuts.” (This directly relates to my earlier point that cornmeal agar has a long history of use in fungal culture.)

It boils down to this: if you have a healthy soil, it will probably contain diverse populations of beneficial microbes, including those that control pathogenic fungi. You don’t need to add cornmeal – it’s simply an expensive form of organic material.  So you can ignore the directions in the article on how to incorporate cornmeal into the soil, or make “cornmeal juice” to spray on “susceptible plants.”   Just nurture your soil with (repeat after me) a thick layer of coarse organic mulch.

(As a footnote, let me say how annoying it is when gardening personalities grant themselves advanced degrees or certifications in their titles.  C’mon folks – if your information is so great, do you really need to pretend you’re someone else?)

(Another footnote: I discussed this myth more in 2012. Be sure to check this link out too.)

UPDATE: Since this is a myth that refuses to die, I’ve published a peer-reviewed fact sheet on the topic. Feel free to pass on to others.

The Other Lamb’s Ears

I’m assuming even you tree people (aka other
Garden Professors) are familiar with the soft, silvery leaves of Stachys
byzantina or Lamb’s Ear (variously Lamb Ears and Lamb’s Ears).  Not to
disparage S. byzantina, but in our part of the world it looks like a
pile of wet dryer lint in the winter; and can become similarly
disfigured during a hot, wet summer.  Spring brings bright,
pet-able new ears, followed by woolly flower spikes that could serve as
Q-tips for Shrek. Runs/reseeds like a banshee in my home garden.
As
Dr. Allan Armitage notes, “We’ve been lamb-eared to death.”

But there are several other species of
garden-worthy Stachys, one of which is garnering lots of attention in
our campus garden at the moment. Behold, Stachys officinalis ‘Hummelo’ – Wood Betony or Alpine
Betony.

Also sold under S.
officinalis and S. densiflora. Most nurseries seemed to have settled on
S. monieri, but that specific epithet does not appear in the ITIS
(Integrated Taxonomic Information Systems) database. Armitage lists it as a cultivar
of S. officinalis and then has S. monieri as a separate species.

Regardless of pedigree, ‘Hummelo’ is a terrific perennial.
Clumps of glossy green scallop-edged foliage are topped with
spikes of rosy-lavender flowers throughout the summer. Heat- and
cold-tolerant; it’s hardy from Zones 4 to 8. Full sun or part shade,
drought tolerant, deer resistant…what’s not to like?

Back to the ubiquitous version of lamb’s ear…we
have a superior selection of S. byzantina with the fabulous cultivar
name of ‘Countess Helene von Stein’. Rarely flowers, and has bigger, tougher leaves that hang in there regardless of humidity. Very effective
when barked at students with a Teutonic accent: “Countess Helene von
Shtein! You vill learn dis plahnt!”  You may find this in
the U.S. under the comparatively boring ‘Big Ears’.

Mystery berry revealed

You guys are just too smart – I was hoping to trap someone into guessing a Vaccinium species. But no, you all knew this was a Taxus spp. (yew):

Because Taxus is a gymnosperm, this reproductive structure is actually a cone.  It’s botanically incorrect to call it a fruit of any sort, as the term "fruit" refers specifically to angiosperms. Taxus cones are modified for seed dispersal to include an edible, fleshy aril (very good, @GardenHoe!), whose taste and color are attractive to birds. The seed (which is toxic, like all vegetative parts of the plant – you’re right, Jimbo!) passes through the gut undigested.

The toxin in Taxus is the alkaloid taxine.  Like many alkaloids, it’s a potent neurotoxin. Other alkaloids you’re more familiar with include caffeine, nicotine, and codeine.

Our visiting Garden Professor and his Kentucky coffeetree

By Dr. Charlie Rohwer

Since my last guest professor submission (buying organic food for health) garnered so much discussion, I thought I’d try to write about a less controversial topic: evolution.  There’s no scientific doubt that’s where plants (well, all species of everything, really) come from, but what got me thinking about it recently was my Kentucky coffeetree.

My wife and I bought our first house a couple years ago, and for the previous 25 years at least, the landscaping had been severely neglected.  Ubiquitous rock mulch on top of plastic, a cherry covered in black knot, and zero space used for any kind of garden, unless you count the 2 sedum suffering under rocks and plastic.  So we made lots of garden space and bought our first tree, a Gymnocladus dioicus.  But as the epithet indicates, Kentucky coffeetree is dioecious.  The plant either has male flowers or female flowers.  We liked the fact this tree will get tall but not spread too wide, tolerate our soil, have interesting bark and leaves, and the winter shade will be fairly sparse, but we didn’t really want to have the big seed pods from the females.  We bought an unsexed plant in 2009 and hoped for the best.  Make no mistake, we were proud parents, regardless of the sex of our newly-planted 7-foot stick.  It flowered this year, with only stamens.  It’s a boy!  But it got me thinking, where and when did its dioecism come from?  It amazed me that I hadn’t considered it before because I actually work with another dioecious plant, hops (Humulus lupulus).

Flowering plants probably started their evolutionary timeline with both male and female parts near each other.  Carpels (female) and stamens (male) are specialized places where male and female gametes (sperm and egg) are made, fused, and the young sporophyte, as a developing embryo, is protected in maternal structures.  Sounds familiar, but as Bert stated in a recent post, we need to strictly avoid teleology.  In fact, though more common in some parts of the world, dioecism is the exception in flowering plant reproduction (<10% of species).  Most flowers you see are hermaphroditic, with both male and female parts together in the same flower.   Dioecism is so dispersed among plant genera, it’s probably evolved many different times, and is thought to arise through a series of evolutionary steps.  For example, in one mechanism, some individuals within a species loose the ability to make pollen (genetically), and some plants within that species can still produce both male and female flowers.  Then selection can act on the two types of plants separately, and at some point, the ability to make female parts disappears in the hermaphroditic line.  But there are different ways to arrive at dioecism that help to explain how it arose multiple times in so many diverse plant lineages.  Genera other than Gymnocladus (a legume) and Humulus (complicated taxonomy, but clearly related to Cannabis) that have evolved to be dioecious include Spinacia (spinach, an amaranth), Pistacia (pistachio, in the cashew family), Asparagus (a monocot), Dioscorea (yam, in the….yam family), and Ginkgo (not even classified as a flowering plant, and not a conifer either!).

Kentucky coffeetree is a legume, but think of every other legume you know and dioecism is the exception, by far.  Pollination and dispersal mechanisms, optimization of reproductive resources, and outcrossing pressure are thought to drive evolution of these species away from hermaphroditic flowers.  Evidently this happened to the Kentucky coffeetree lineage by 50 million years ago.  About 40 percent of the time that flowering plants have existed, Gymnocladus has been dioecious.  That’s 1 million times longer than a 50-year-old person has existed.  Dinosaurs had been extinct for 15 million years or so by the time the Kentucky coffeetree lineage split from other legumes.  Those are numbers we have a hard time grasping because natural processes have been around a lot longer than we have.

 

Reading:

Ainsworth, 2000. Boys and girls come out to play: the molecular biology of dioecious plants. Ann. Bot. 86:211–221.

Doyle and Luckow, 2003. The rest of the iceberg. Legume diversity and evolution in a phylogenetic context. Plant Physiology 131:900–910.

Specht and Bartlett, 2009. Flower evolution: the origin and subsequent diversification of the angiosperm flower. Ann. Rev. Ecol. Evol. Syst. 40:217–243.

Here’s the plant food everyone is talking about!

Apparently I don’t talk to the right people; I’d never heard of this product until newbie gardener and longtime skeptic John emailed me about Eleanor’s VF-11 plant food.

Upon visiting the website, this is what I learned about VF-11 and roses (the rose aficionado market is apparently a lucrative one for snake oil salesmen):

Point: “VF-11 Plant Food is not a ‘push’ like other fertilizers…think of it as a strength and health builder.”

Counterpoint: It certainly is not a fertilizer. It doesn’t contain enough minerals to do anything for a plant. So why not just use water? There’s something that can work miracles on drought-stressed plants!

Point: “VF-11 builds so much strength and health in your roses that plant cells ‘harden’ and ‘seal in the amino acids’.”

Counterpoint: I will kindly label this as nonsense since this is a G-rated blog. It says nothing but sounds sciency.

Point: “When you’re Foliar Feeding your roses, no need to worry if it blows back into your face. It’s gentle, gentle, gentle and safe.”

Counterpoint: Foliar feeding is an ineffective way of fertilizing plants (you can read more about in a column I wrote some time ago). In short, foliar application of specific nutrients is an excellent way of determining whether a deficiency of that nutrient exists, but it does nothing for the plant on a long-term basis.  I won’t beat that dead horse any longer. And thanks, I’d rather not have stuff blown in my face, regardless of what’s in it.

And more amazing facts elsewhere on the site:

Point: “And you do not need a lot of additives in your soil, like compost etc.”

Counterpoint: Wow. Who knew that organic matter was bad?

Point: “It’s an electrolyte balanced solution.”

Counterpoint: So’s urine. And urine has more nitrogen. (I won’t enter the debate about peeing on your plants.)

Evidence?

For evidence, the site offers two tissues analyses of pistachios that were sprayed with VF-11 (the foliar feeding method). The previous year (no VF-11) the leaves had high levels of copper and low levels of boron and magnesium. After treatment, the copper was reduced and boron and magnesium improved. Since boron and magnesium are not in the product, perhaps the copper was somehow transmuted into boron and magnesium? I can’t think of a more rational explanation if VF-11 is the causative agent. But I can think of lots of reasons this variation might happen from year to year, including the use of copper fungicides and the ability of some nutrients to restrict the uptake of others.

There’s also tissue analyses from a “sick vineyard” taken in June, then repeated in October after foliar application of VF-11. Both potassium and magnesium are singled out for note, though the ratings information is strangely missing (in other words, there’s no notation whether the levels are deficient, sufficient, or excessive). The differences between the %K and %Mg are circled for one sample, though a quick statistical analysis of all 4 samples show no significant differences between dates.  And even if there were – does anyone really expect leaf nutrient levels to be the same in June as in October? Keep in mind that the plant is both producing fruit and preparing for dormancy. Nutrients do move around!

Where did this magical recipe come from?

Again, relying on garden forums for my information (since the product website is vague on the topic), Eleanor “got the formula from a “cantankerous” elderly chemist who grew healthy plants, including tomato plants that were 30 ft. long.”

What’s actually in this miracle product?

According to the Washington State’s fertilizer product database (a really helpful resource for anyone, not just Washington residents), it is 0.15% N, 0.85% P, and 0.55% K (yes, these are all less than 1%). It also contains 3.5 ppm zinc and 3.2 ppm molybdenum. Products with such minute levels of minerals really aren’t fertilizer, but they really aren’t plant food either. Once this is diluted, you are left with…water. This is uncomfortably similar to homeopathic “cell salts,” which are highly diluted mineral products used to prevent disease in humans. Coincidentally, fans of Eleanor’s potions report that VF stands for Verticillium/Fusarium, “signifying that it creates disease resistance”. Hmm.

As Dr. Barrett points out on his QuackWatch site about homeopathic cell salts, “many are so diluted that they could not correct a mineral deficiency even if one were present.” I would venture the same would be true in plants. Again, Eleanor’s aficionados report that the “11” in the name “signifies it has eleven ingredients include iron, boron, copper, zinc, and molybdenum.” Hmm. Washington State’s analysis lab couldn’t find either iron or boron. Or whatever the other 4 minerals might be (besides the nitrogen, phosphorus, potassium, molybdenum and zinc).

Finally, the most bizarre use of this product must be the one reported by another fan of Eleanor’s: “Eleanor called me this evening and she could hear my parrots in the background…she told me that she, too, has birds. She then went on to explain that a woman told her that her birds looked terrible and that she started to spray them with Eleanor’s VF-11…an amazing improvement in both their plumage and in their attitudes…so, Eleanor did a test with hundreds of birds…and confirmed that spraying your birds often with the same mixture of VF-11 and water…room temperature…would enhance their feathering and make them much happier!

“Eleanor believes that indoor pets miss out on a lot of necessary nutrition due to being indoors….she stated the importance of animals and birds of being exposed to “dew”. I always assumed that dew was just water…but, Eleanor believes it contains nutrients.”

I think I need to stop now.

Is Black The New Brown?

Mulch is always an interesting point of discussion as well as the topic of several past GP posts. But I honestly can’t recall if we’ve covered dyed mulch, and can’t search the site, so here goes.

I recently received a request for information from Debbie Dillon, a fine Urban Horticulturist with Virginia Cooperative Extension.  She noted the increased use of dyed mulch in the Northern Virginia area, and has been fielding questions from both landscape designers and homeowners regarding the safety of said mulch and the potential for harmful effects on plants. Black seems to be a fave color of late.

All I could offer her at the time was “Bleccch, I really don’t care for it” and a promise to investigate further. Armed with a bit of spare time and Google – here’s what [little] I’ve found out.

There are several products out there, such as Solarfast MCH and Mulch Magic. They’re used commercially on bulk mulch and are also available to the homeowner without restriction. From the Solarfast website – “Solarfast MCH is a colorant used to restore faded mulch back to its original color. It is environmentally friendly and does not contain hazardous chemicals, heavy metals or other ingredients that are known to be harmful to the environment.”

Is it safe?

The MSDS (Material Safety Data Sheet) for Solarfast was incomplete – it did not list components. The MSDS for Mulch Magic indicates the black contains carbon black, red contains iron oxide, and brown contains diethylene glycol monobutyl ether (as well as carbon black and iron oxide). The composition beyond that (carriers, surfactants, etc.), was not noted.  Diethylene glycol monobutyl ether is a fairly common solvent for paints and inks with purportedly low environmental toxicity, but can irritate skin and eyes. Carbon black can be made from various sources but is basically a petroleum product, used in laser printer and photocopier toner as well as the manufacture of reinforced rubber (i.e. tires).  Most concerns are related to worker inhalation at the point of manufacture. Iron oxide is, well, oxidized iron, and has been used as a pigment for quite a while (i.e. cave paintings at Lascaux, Bob Ross, etc.).

What about the plants?

There are many, many studies on pigmented film mulches (usually polyethylene) in fruit and vegetable production.  Certain colors can alter plant growth and processes, such as flowering and fruiting, stem length, etc., but I couldn’t find a thing regarding dyed, wood-product mulch. Issues of concern might be that the dye is disguising the composition of the mulch. Apparently dyes are frequently used on “pallet mulch” – shredded pallets, usually made from softwood. Another concern might be the increase in root-zone temperature, especially from the use of heat-absorbing black pigments. Could soil temperatures warm to the point of causing a too-early bud break?

Is it aesthetically pleasing?

Apparently “yes”, to some, because there’s a market for it. What do you think?


This photo was taken in April at a local medical center (it was a rainy morning, pardon the low light). The fairly typical commercial landscape surrounding the building is dotted with beds and trees freshly mulched in black. Note the classic mulch “volcano” in the background. No sir, I don’t like it. But that’s just me.

Toxicity information on compounds noted available at the International Agency for Research on Cancer (IARC) – Summaries &  Evaluations,  http://www.inchem.org/